1. Field of the Invention
The present invention relates to a valve stem assembly in internal combustion engines.
2. Description of the Prior Art
Heretofore various means have been developed for the purpose of attaching a valve spring retainer to the distal end of the valve stem.
One prior means utilizes two wedge-shaped key members. Each key member includes a projection for extending into a recess in the distal end of the valve stem to accurately position each key member on the distal end of the valve stem with the upper portion of each key member being substantially flush with the tip of the distal end of the valve stem. However, this device is disadvantageous since, for example, a normal cup-shaped lash cap cannot be used therewith.
A similar prior means of attaching a valve stem to a valve spring retainer is one developed by Chrysler Corporation for use in its 426 Hemi engine and is composed of two key members similar to the above means but the top of each key member is removed to accomodate a cup-shaped lash cap in a recess then formed between the side of the distal end of the valve stem and the inner edge of the valve stem retainer. One purpose of the lash cap is to present an enlarged bearing surface for the rocker arm to contact as will be apparent to those skilled in the art. However, this means is disadvantageous in that when the upper portion of the key members is removed the lock will lose a great deal of strength making it disadvantageous for use in certain conditions.
Another prior means was developed by Crane Cams and is similar in that each of the two key members (identified by the Crane Cams part number 99093) has a projection for extending into a groove in the distal end of the valve stem and the upper portion of each wedge-shaped key member is again removed for receiving the lash cap, but the upper portion of these key members is thicker than the above described key members. Each of these key members is also longer than the Chrysler Corporation key members because Crane Cams extended the lower portion down the side of the valve stem. However, due to the inherent weakness caused by the loss of the upper portion this device is still disadvantageous in extreme conditions.
Heretofore, various patents have been issued relating generally to the present invention. See, for example: Engemann, U.S. Pat. No. 2,827,891; Cousino, U.S. Pat. No. 3,021,593; Bush, U.S. Pat. No. 3,077,874; Thompson, U.S. Pat. No. 3,298,337; Iskenderian, U.S. Pat. No. 3,853,101; and Toth, U.S. Pat. No. 3,978,830. None of the above patents disclose or suggest the present invention.